CHARACTERIZATION OF GE OUTDIFFUSION AND SI CAP THICKNESS IN STRAINED SI/SIGE STRUCTURES BY SIMS

摘要

The outdiffusion of Ge from the SiGe underlayer into the thin Si cap layer in strained Si/SiGe material systems can affect the mobility of carriers in the channel, and in extreme cases the channel thickness or even the gate oxide integrity. This outdiffusion can be affected by epi growth temperature, rate and source gas, as well as by point defects at the Si/SiGe interface. The Si cap layer is very thin, on the order of 10 nm, such that the required depth resolution information of Ge outdiffusion is very challenging. This paper focuses on the SIMS measurement of the Ge outdiffusion and the Si cap thickness, and the accuracy and precision of the Ge measurement.